1. Field of the Invention
The present invention relates to a passenger seat air bag, and particularly relates to a so-called planar air bag for a passenger seat comprising a bottom wall portion having an aperture portion for inflating gas inlet; and a ceiling wall portion having an outer shape substantially the same as that of the bottom wall portion and disposed in opposition to the bottom wall portion; wherein outer circumferential edges of the bottom wall portion and the ceiling wall portion are coupled with each other so as to form a bag.
2. Description of the Related Art
In the background art, such a planar air bag for a passenger seat had two fabric sheets of a bottom wall portion having an aperture portion for inflating gas inlet, and a ceiling wall portion disposed in opposition to the bottom wall portion, the outer circumferential edges of the bottom wall portion and the ceiling wall portion being coupled with each other so as to form a bag, as disclosed in the publication of Unexamined Japanese Patent Publication Hei. 7-291068.
Such a passenger seat planar air bag was folded and received as follow. First, the bottom wall portion and the ceiling wall portion were put on top of each other so that the air bag was unfolded to be flat. Then, the air bag was folded so that the circumferential edges were made close to the aperture portion. Thus, the air bag was received in a case of the passenger seat air bag system, and the case was disposed in a portion of an instrument panel.
Incidentally, in the air bag disclosed in the above publication, the aperture portion provided in the bottom wall portion was offset toward the vehicle rear side so that the projection quantity toward the vehicle rear side when the air bag had finished inflating was increased by the interference with a wind shield.
However, in the case where the aperture portion for inflating gas inlet is disposed substantially at the center of the bottom wall portion differently from the above publication, if the bottom wall portion and the ceiling wall portion are put on top of each other so that the air bag is unfolded to be flat, and if the air bag is folded so that the outer circumferential edges of the bottom and ceiling wall portions are made close to the aperture portion, the vicinity of the center of the ceiling wall portion in opposition to the aperture portion inflates partially so as to project toward the vehicle rear side at the beginning of inflating. Particularly, the vicinity of the center of the ceiling wall portion is apt to project away from the vicinities of the outer circumferential edges sewed with each other. Thus, the distance with which the air bag projects partially at the beginning of inflating becomes long. Then, if a passenger is bound in the middle of the inflating, high pressure is given to the passenger because the projecting portion projects not over a wide area but partially.
Further, in the background art, an air bag used in a passenger seat air bag system was expected to move backward in the state where it was unfolded in a wide area so as to be a substantially vertical plane when it was unfolded and inflated (refer to Unexamined Japanese Patent Publication No. Hei. 11-278192, or the like).
However, in a top mount type passenger seat air bag system disposed on the top surface of an instrument panel in front of a passenger seat, in such a case where a child was close to the instrument panel, an air bag might be expected to be unfolded quickly along the passenger seat side surface of the instrument panel, that is, along the rear surface of the instrument panel from the top surface thereof at the beginning when the air bag was unfolded and inflated, so that a portion of the air bag was disposed between the child and the rear surface of the instrument panel.
It is therefore an object of the present invention to solve the foregoing problems, that is, to provide a passenger seat air bag in which, though the air bag is a planar one having an aperture portion for inflating gas inlet disposed substantially at the center of a bottom wall portion, the air bag is restrained from projecting partially at the beginning of inflating so that a passenger can be bound with a wide area even if the passenger is bound in the middle of the inflating.
It is another object of the present invention to solve the forgoing problems, that is, to provide a passenger seat air bag which can be unfolded quickly along a passenger seat side surface of an instrument panel at the beginning when the air bag is unfolded and inflated.
According to a first aspect of the present invention, there is provided a passenger seat air bag comprising a bottom wall portion having an aperture portion for inflating gas inlet provided substantially at a center of the bottom wall portion, and a ceiling wall portion having an outer shape substantially the same as that of the bottom wall portion and disposed in opposition to the bottom wall portion, respective outer circumferential edges of the bottom and ceiling wall portions being coupled with each other so as to form a bag, the air bag being folded in a state where the bottom wall portion and the ceiling wall portion are put on top of each other so that the air bag is unfolded to be flat, the folded air bag being received in a portion of an instrument panel so that the circumferential edges are made close to the aperture portion, wherein at the beginning of folding, while the state where the bottom wall portion and the ceiling wall portion are put on top of each other so that the air bag is unfolded to be flat is kept, a coupling portion on the vehicle front side where the bottom wall portion and the ceiling wall portion are coupled with each other is shifted toward the vehicle rear side, and the air bag is folded and received in this state so that the circumferential edges are made close to the aperture portion.
According to a second aspect of the present invention, there is provided a passenger seat air bag comprising a bottom wall portion having an aperture portion for inflating gas inlet provided substantially at a center of the bottom wall portion, and a ceiling wall portion having an outer shape substantially the same as that of the bottom wall portion and disposed in opposition to the bottom wall portion, respective outer circumferential edges of the bottom and ceiling wall portions being coupled with each other so as to form a bag, the air bag being folded in a state where the bottom wall portion and the ceiling wall portion are put on top of each other so that the air bag is unfolded to be flat, the folded air bag being received in a portion of an instrument panel so that the circumferential edges are made close to the aperture portion, wherein the air bag further comprises a band-like tether for generating tension in the air bag at the time of inflating so as to restrain the shape of the air bag upon completion of the inflating, the tether being disposed in the air bag in a manner so that one end portion of the tether is coupled with a rear edge of the bottom wall portion on the vehicle rear side in a circumferential edge of the aperture portion, while the other end portion of the tether is coupled with a position on the vehicle front side of the center vicinity of the ceiling wall portion.
According to a third aspect of the present invention, there is provided a passenger seat air bag used in a passenger seat air bag system disposed on a top surface of an instrument panel in front of a passenger seat in a vehicle, the air bag comprising a gas inlet disposed substantially along a horizontal plane, and a flow control cloth provided inside a body of the air bag so as to cover the gas inlet for changing a flow of inflating gas allowed to flow in through the gas inlet, wherein the flow control cloth is disposed so as not only to cover the gas inlet in a left/right direction of the vehicle but also to make a flow rate of the inflating gas flowing toward a rear side higher than a flow rate of the inflating gas flowing toward a front side with respect to a substantially middle portion in a front/rear direction of the flow control cloth.
In the above passenger seat air bag according to the third aspect of the present invention, in order to make the flow rate of the inflating gas flowing toward the front side lower than the flow rate of the inflating gas flowing toward the rear side thereof with respect to the substantially middle portion in the front/rear direction of the flow control cloth, the flow control cloth is disposed so that left and right edges of the flow control cloth are coupled with a circumferential edge of the gas inlet in an inner circumferential surface of the air bag body while front and rear edges of the flow control cloth are not coupled with the air bag body, and gas communication holes for allowing the inflating gas to pass therethrough may be disposed in the left and right sides of the rear edge of the flow control cloth.
In the above passenger seat air bag according to the third aspect of the present invention, in order to make the flow rate of the inflating gas flowing toward the front side lower than the flow rate of the inflating gas flowing toward the rear side thereof with respect to the substantially middle portion in the front/rear direction of the flow control cloth, the flow control cloth is disposed so that left and right edges and a front edge of the flow control cloth are coupled with a circumferential edge of the gas inlet in an inner circumferential surface of the air bag body while a rear edge of the flow control cloth is not coupled with the air bag body, and gas communication holes for allowing the inflating gas to pass therethrough are disposed, respectively, between each of the left and right edges of the flow control cloth near the front edge and the air bag body or in vicinities of left and right sides near the front edge of the flow control cloth itself.
In the above passenger seat air bag according to the third aspect of the present invention, the rear edge of the flow control cloth is connected, through a connecting belt, with a rear edge of the circumferential edge of the gas inlet in the air bag body so that forward movement of the inflating gas can be restricted when the inflating gas flows in through the gas inlet.
In the passenger seat air bag according to the first aspect of the present invention, the portion of the ceiling wall portion in opposition to the aperture portion projects first when inflating gas flows into the air bag through the aperture portion of the bottom wall portion.
In the air bag according to the first aspect of the present invention, however, the coupling portion on the vehicle front side where the outer circumferential edges of the bottom wall portion and the ceiling wall portion are coupled with each other is shifted toward the vehicle rear side at the beginning of folding. Thus, the portion of the ceiling wall portion in opposition to the aperture portion is away from the vicinity of the center of the ceiling wall portion, and close to the vicinity of the coupling portion on the vehicle front side where the outer circumferential edges of the bottom wall portion and the ceiling wall portion are coupled with each other. As a result, the initial projecting quantity at the beginning of the inflating can be restrained.
In addition, since the vicinity of the center of the ceiling wall portion which is apt to inflate is shifted toward the vehicle rear side at the beginning of folding, the vicinity of the center of the ceiling wall portion which is apt to inflate also starts to project toward the rear side in the middle of the inflating. Thus, the vicinity of the center of the ceiling wall portion together with the portion initially projecting at the beginning of the inflating projects toward the rear side over a wide area.
Further, when the vicinity of the center of the ceiling wall portion shifted toward the vehicle rear side at the beginning of folding starts to project to the rear side, a moment to rotate the ceiling wall portion toward the rear side acts on the air bag so that the portion initially projecting at the beginning of the inflating and the vicinity of the center of the ceiling wall portion become substantially parallel with a vertical plane.
Thus, in the passenger seat air bag according to the first aspect of the present invention, though the air bag is a planar one having an aperture portion for inflating gas inlet disposed substantially at the center of a bottom wall portion, the air bag can be restrained from projecting partially at the beginning of inflating so that a passenger can be bound with a wide vertical area even if the passenger is bound in the middle of the inflating. It is therefore possible to reduce the pressure given to the passenger.
In the passenger seat air bag according to the second aspect of the present invention, when inflating gas flows into the air bag through the aperture portion, the inflating gas is guided by the tether so as to flow from the vicinity of the center of the ceiling wall portion toward the vehicle front side and hence makes the portion where the inflating gas flows project.
However, the projecting portion is regulated by the tether so as not to project not more than the length of the tether let out. Thus, the initial projecting quantity at the beginning of the inflating is restrained.
Moreover, the vicinity of the center of the ceiling portion which is apt to inflate also starts to project backward and projects backward over a wide area together with the portion initially projecting at the beginning of the inflating.
Further, the tether is disposed so as to be coupled between the rear circumferential edge of the aperture portion of the bottom wall portion at the vehicle rear side and the portion of the vicinity of the center of the ceiling wall portion at the vehicle front side so as to cover the vehicle rear side of the aperture portion. Thus, if the inflating gas interferes with the tether, the tether gives the air bag a moment to rotate the ceiling wall portion toward the rear side. As a result, the portion initially projecting at the beginning of the inflating and the vicinity of the center of the ceiling wall portion become substantially parallel with a vertical plane.
Therefore, also in the passenger seat air bag according to the second aspect of the present invention, though the air bag is a planar one having an aperture portion for inflating gas inlet disposed substantially at the center of a bottom wall portion, the air bag can be restrained from projecting partially at the beginning of inflating so that a passenger can be bound with a wide vertical area even if the passenger is bound in the middle of the inflating. It is therefore possible to reduce the pressure given to the passenger.
In the passenger seat air bag according to the third aspect of the present invention, the flow control cloth is disposed in the left/right direction of the vehicle so as to cover the gas inlet. As a result, when the air bag is unfolded and inflated, the flow rate of the inflating gas flowing toward the rear side of the approximately middle portion in the front/rear direction of the flow control cloth becomes higher than the flow rate of the inflating gas flowing toward the front side thereof. Thus, the lower portion of the air bag is easy to deploy along the rear surface of the instrument panel from the top surface thereof.
As a result, the passenger seat air bag according to the present invention can be unfolded quickly along the passenger seat side surface of the instrument panel at the beginning when the air bag is unfolded and inflated.
In the air bag according to the third aspect of the present invention, the gas communication holes for allowing the inflating gas to pass therethrough are disposed, respectively, on the left and right sides of the rear edge of the flow control cloth itself. As a result, when the lower portion of the air bag is deployed along the rear surface of the instrument panel from the top surface thereof at the beginning when the air bag is unfolded and inflated, the lower portion of the air bag can be unfolded with a broad width in the left/right direction.
In the air bag according to the third aspect of the present invention, substantially the three sides except the rear edge, that is, the front side and the left and right sides of the flow control cloth are coupled with the air bag body except the gas communication holes near the left and right sides of the front edge of the air bag body. As a result, at the beginning when the air bag is unfolded and inflated, the flow control cloth is first inflated like a bag, and next a large quantity of the inflating gas flows from the rear edge of the flow control cloth to the lower portion of the air bag. At that time, an air bag cover covering the folded air bag can be opened smoothly when the flow control cloth is inflated like a bag. Next in that state, a large quantity of the inflating gas flows to the lower portion of the air bag so that the lower portion of the air bag deploys along the rear surface of the instrument panel from the top surface thereof more easily. As a result, the air bag can be unfolded more quickly along the passenger seat side surface of the instrument panel at the beginning when the air bag is unfolded and inflated.
Further, in the air bag according to the third aspect of the present invention, the forward movement of the rear edge of the flow control cloth is restricted by the connecting belt which is connected to the circumferential edge of the gas inlet. Accordingly, when the inflating gas flows in, it is possible to avoid such a state that the flow control cloth is turned over forward so as to open the gas inlet directly in the air bag body. As a result, the flow rate of the inflating gas flowing backward can be made stably higher than the flow rate of the inflating gas flowing forward.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.